Art of refining copper



Patented Nov. 15, 1927.

UNITEDSTATES 1,648,947 PATENT OFFICE.

ERNEST H. JACOBSgOF CHICAGO, ILLINOIS, ASSIGNOR TO ELECTRICAL ENGINEERS EQUIPMENT COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

em: or REFINING COPPER.

No Drawing.

My invention relates to the art of casting pure copper. g

In the electrical industry it is highly desirable that pure copper of high conductivity be employed particularly in connection with heavy current conducting apparatus Where great amounts of cast copper are employed.

The desirability for a low resistance is obvious where high current values prevail because the I R losses run into large quan tities.

Whereas the prior art has known it to be desirable to reduce the resistance, or in other terms increase the conductivity, of such metal as is used in the transmission of heavy electric current, there has not been on the market any commercially successful method of casting copper which would bring the conductivity any higher than from 4.0 to of that of rolled copper.

Where the conductivity is low there is not only the loss in power due to heating, but also a tendency to increase the weight of the castings in an attempt to gain greater conductivity with a consequently greater investment in copper and consequently greater fixed interest charge for the station. According to my invention it is possible to produce copper Which is substantially chemically pure, which has a beautiful copper color, great density and high conductivity of the order of from 80 to 90% of that of rolled copper and in some cases higher than 90%.

In order to secure copper of this character; I employ a reducing agent or what I term herein a flux or alloy for purifying the molten copper just before it is cast into the mold.

This reducing agent or alloy is produced as follows:

First I take in the proportion of 10 pounds of phosphor copper and melt the same in a crucible under a thin blanket or covering of charcoal. This is an alley or metal which is well known and which I buy in the open market. The material in the crucible is still covered with charcoal and is thoroughly melted. Then I add in the proportion of one pound of copper sulphate. After these ingredients are brought to the liquid state I then add in the proportion of onehalf pound of fluorspar and after the above ingredients are brought to the liquid state by heating to melt the same, I add the final ingredient Application filed March 26, 1923. Serial No. 627,566.

of and in the proportion of one-half pound of boraX. This is then all finally brought to molten condition, the top of the crucible still being covered by a thin covering or blanket of charcoal. The above alloy or flux is then cast into rods or thin strips in a suitable open or closed mold.

In the process of casting the copper I employ the flux or alloy as above prepared according to the following procedure.

Thecopper for producing castings which should be as clear as possible is melted in a crucible kept covered by a layer or blanket of charcoal. It is advisable to melt the copper in small crucibles.

Then, just as the crucibles are taken from the furnace prior to pouring I add the above flux or alloy in substantially the proportion of 9 ounces of flux or alloy to 200 pounds of molten copper. The above ratio is in approximately the proportion of one half ounce of the alloy for each 10 pounds of molten copper.

In making the molds it is desirable to lay the castings flatwise, that is to say, with as little depth in the casting as possible, and to employ a relatively large and free sprue in proportion to the gate so that by gravity the lighter ingredients may separate into the top of the sprue and the denser copper remain at the bottom and form the casting.

Castings made according to the above procedure have a beautiful copper color, have a very high conductivity of the order of 80 to of that of rolled copper of a conductivity of Matthieson standard and are substantially chemically pure. It appears that the ingredients which make up the flux or alloy disappear from the main body of the copper and consequently they do not appear in a chemical analysis of the castings.

I do not intend to be limited to the precise formula and method of procedure above stated, because in some instances where the impurities of the copper supply the necessary re-agents or render them unnecessary they may be reduced or dispensed With. However, I have conducted considerable experimentation and have tested various deviations from the above formula but find them to be less satisfactory than the process and formula above outlined. This process and formula secures, so far as I can find, uniform results and the resulting castings are as I find by a period of testing them in actual use, not subject to deterioration through ageing or Weathering.

I claim: a

1. The process of casting copper which comprises melting under a blanket of reducing material such as charcoal, a batch of copper, and adding to the melted copper a conditioning or purifying alloy or flux in approximately the proportion of 9 ounces of said alloy or flux to 200 pounds of copper, said flux being added just prior to pouring the copper, comprising substantially the following constituents, namely, copper 10 pounds, phosphor copper three pounds, copper sulphate one pound, fluorspar one half pound, and borax one half pound.

2. The process of making a flux for casting copper which comprises melting under a charcoal blanket, 10 pounds of copper, adding three pounds of phosphor copper, bringing the resulting material to a liquid state by heating, then adding one pound of copper sulphate and again bringing the re sulting material to a liquid state by heating, then adding one half'pound of fiuorspar and again. bringing the resultin material to a liquid state by heating and half pound of borax and bringing'the resulting material to a liquid state by heating.

3. A reducing agent or flux for molten copper consisting of the following ingredients in substantially the following proportions:

In Witness whereof, I hereunto subscribe my name this 24 day of March, 1923.

ERNEST H. JAooBs.

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